Near Repeat calculator

Use this site to download a free software program that calculates the risk of near repeat events in crime data


This software originates with the relatively recent discovery of the near repeat phenomenon in burglary patterns, a discovery that has highlighted the communicability of crime events that affect the risk level at nearby locations. The near repeat phenomenon states that if a location is the target of a crime (such as burglary), the homes within a relatively short distance have an increased chance of being burgled for a limited number of weeks (Townsley et al, 2003; Bowers and Johnson, 2004; Johnson and Bowers, 2004a, 2004b). This communicability of risk to nearby locations for a short amount of time raises the possibility that other crime types may also suffer from a near repeat spatio-temporal pattern of behavior.

The analytical method employed builds on a space-time clustering methods first pioneered by Knox (1964) to study the epidemiology of childhood leukemia. The Knox test seeks to determine whether there are more event-pairs observed that occur with a closer proximity in space and time than would be expected on the basis of a random distribution. To do this, each shooting for a particular dataset is compared with every other and the spatial and temporal distance between them recorded. The result is a matrix of space-time distances.

To establish a null hypothesis measure against which to test the shooting patterns, we employ a Monte Carlo simulation process. By computing multiple simulations of the expected values, it is possible to generate an expected distribution under a null hypothesis using the actual study data. This provides a unique way to examine what would occur if there were no near repeat patterns.

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 !    What are near repeats?
The near-repeat phenomenon states that if a location is the target of a crime (such as burglary), then locations within a relatively short distance have an increased chance of being burgled for a limited period of time.

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